Heat pipe with ultra-thin capillary structure

ABSTRACT

A heat pipe with an ultra-thin capillary structure includes a tube body which is hollow and flat, and a capillary structure which is in the tube body and is shaped as a thin plate. The capillary structure has an adhering surface attached on a partial portion of an inner wall of the tube body, and a forming surface corresponding to the adhering surface. A vapor channel formed between the forming surface and the inner wall of the tube body; wherein the forming surface further includes an abutting surface elongated along a longitudinal direction of the vapor channel and at least one capillary transmission surface extending from a side of the abutting surface to connect to the adhering surface the steam channel, and the capillary transmission surface is gradually inclined between the adhering surface and the abutting surface.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to a miniaturized heat pipe, more particularly to a heat pipe with an ultra-thin capillary structure.

2. Description of the Prior Art

Nowadays, electronic products are tending to small volumes in order to be easily carried. Since the volumes are smaller, some kinds of electronic products that need to dissipate heat inside should focus on the issue of the volume of a heat pipe. In order to minimize the heat pipe in the electronic products, an ultra-thin heat pipe, which has thickness under 1.5 mm, is then developed.

However, a capillary structure inside the ultra-thin heat pipe shall follow the design tendency to be smaller as well. To design the capillary structure, it may focus on the inner space of a heat pipe in order to avoid that the inner space is too small to let air or fluid be through. That is, when an ultra-thin heat pipe is manufactured in a sintering process, its volume is designed very small to cause that metal powders are not able to be through a gap between a mandrel bar and the inner wall of the ultra-thin heat pipe, and part of the metal powders may not be positioned in the ultra-thin heat pipe. That is why a powdered capillary structure of an ultra-thin heat pipe is only formed at a location of the heat pipe without completion in prior arts. As a conclusion, a sectional surface of an ultra-thin heat pipe is hardly filled with the powdered capillary structure in prior arts. As it can be seen, this kind of powdered capillary structure may be short of a better vaporization surface area, a better condensation surface area, a better liquid transmission sectional surface area, a fluent vapor channel, and a reinforced supporting structure, and we would know the prior ultra-thin heat pipe should be improved in the aspect of heat transmission.

Accordingly, how to improve the heat transmission of an ultra-thin heat pipe in prior arts is an important issue to the people skilled in the art.

SUMMARY OF THE INVENTION

In one aspect, the present invention is to provide a heat pipe with an ultra-thin capillary structure. It is to form a miniaturized capillary structure on an inner wall of a heat pipe in order to maintain an enough space of a vapor channel for heat exchange, for example vaporization and condensation. Furthermore, the heat pipe has a largest capillary surface area and a liquid transmission sectional area, so as to approach the aspect with a miniaturized heat pipe.

In order to perform the above aspect, a heat pipe with an ultra-thin capillary structure provided by the present invention comprises a tube body which is hollow and flat, and a capillary structure which is in the tube body and is shaped as a thin plate. The capillary structure has an adhering surface attaching on a partial portion of an inner wall of the tube body, and a forming surface corresponding to the adhering surface. A vapor channel is formed between the forming surface and the inner wall of the tube body; wherein the forming surface further comprises an abutting surface elongated along a longitudinal direction of the vapor channel and at least one capillary transmission surface extending from a side of the abutting surface to connect to the adhering surface , and the capillary transmission surface is gradually inclined between the adhering surface and the abutting surface.

BRIEF DESCRIPTION OF THE DRAWINGS

The objects, spirits, and advantages of the preferred embodiments of the present invention will be readily understood by the accompanying drawings and detailed descriptions, wherein:

FIG. 1 illustrates a schematic perspective view according to the present invention;

FIG. 2 illustrates a schematic cross-sectional view of a section 2-2 of FIG. 1 according to the present invention;

FIG. 3 illustrates a schematic cross-sectional view of a second embodiment according to the present invention based on a view direction of FIG. 2;

FIG. 4 illustrates a schematic perspective view of a third embodiment according to the present invention;

FIG. 5 illustrates a schematic perspective view of a fourth embodiment according to the present invention;

FIG. 6 illustrates a schematic perspective view of a fifth embodiment according to the present invention; and

FIG. 7 illustrates a schematic partial and enlarged sectional view inside a tube body of the fifth embodiment according to the present invention;

DETAILED DESCRIPTION OF THE INVENTION

Following preferred embodiments and figures will be described in detail so as to achieve aforesaid objects.

Please refer to FIG. 1 and FIG. 2, which illustrate a schematic perspective view and a schematic cross-sectional view of a section 2-2 of FIG. 1 according to the present invention. The present invention provides a heat pipe with an ultra-thin capillary structure. The heat pipe comprises a tube body 1 that is hollow and flat, and at least one capillary structure 2 that is in the tube body 1 and contacts with partial inner walls of the tube body 1. The tube body 1 is formed by a pressing process, and is a flat type with a thickness under 0.5 mm. When the tube body 1 is formed, the tube body 1 comprises an upper wall 10, a lower wall 11, and a plurality of side edges 12, wherein the upper wall 10 and the lower wall 11 are arranged corresponding to each other, and the side edges 12 are connected between the upper wall 10 and the lower wall 11.

As shown in FIG. 2, the capillary structure 2 is disposed in the tube body 1. The capillary structure 2 is made by knit, fiber, sintered metal powders, or any of their combination, in order to form a shape of thin plate. Prior to dispose the capillary structure 2 in the tube body 1, the capillary structure 2 is made. As a matter of fact, the capillary structure 2 is placed in the tube body 1 and simultaneously pressed with the tube body 1. The capillary structure 2 has an adhering surface 20 attached on a partial portion of an inner wall of the tube body 1, and a forming surface 21 with a continuous concave arc corresponding to the adhering surface 20. As aforesaid, the adhering surface 20 is positioned on the partial portion of the inner wall, for example the inner surface of the lower wall 11, of the tube body 1. After the tube body 1 is pressed to be flat, the inner wall, for example the inner surface of the upper wall 10, of the tube body 1 abuts on a partial portion of the forming surface 21 of the capillary structure 2. Continuously, a vapor channel 100 is formed between the rest portion of the forming surface 21 and the upper wall 10, the inner wall 11, and one of the side edges 12 inside the tube body 1. In particular, the adhering surface 20 is elongated along a longitudinal direction of the vapor channel 100, and a porosity of the forming surface 21 is gradually reduced as the forming surface 21 is extended toward the adhering surface 20. Factor in the formation of the porosity feature of the forming surface 21 is that the capillary structure 2 is extruded by the pressing process.

In the preferred embodiment of the present invention, the forming surface 21 has an abutting surface 210 that is attached on the inner surface of the upper wall 10 and elongated along a longitudinal direction of the vapor channel 100, and at least one capillary transmission surface 211 that extends from a side of the abutting surface 210 to connect to the adhering surface 20. In particular, the capillary transmission surface 211 is gradually inclined between the adhering surface 20 and the abutting surface 210. The benefits of the inclined capillary transmission surface 211 are to increase a surface area between the capillary structure 2 and the vapor channel 100, reduce flow resistance of vapor flow, and increase a capillary surface area of working fluid flowing back to the capillary structure 2, in order to achieve a better heat-exchange rate, even though the capillary structure 2 is thinned. As it can be seen, the present invention discloses that two sides of the capillary structure 2 form the two vapor channels 100 and the two capillary transmission surfaces 211, respectively. As shown in FIG. 3, the two capillary transmission surfaces 211 of the capillary structure 2 can be asymmetrical, but in FIG. 2, there is a symmetrical arrangement.

As shown in FIG. 4, the capillary structure 2 is formed with at least one bare area 22. In particular, at a portion of the capillary structure, the capillary transmission surface 211 formed at the one side or both capillary transmission surfaces 211 respectively formed at two sides of the forming surface 21 are removed to separately form one or more bare areas 22. Besides, the bare areas 22 can be formed at a transmission section between a vaporizing section and a condensation section of a heat pipe. Furthermore, the capillary transmission surface 211 can have a plurality of air flow holes 220 exposing inner surface of the lower wall 11 of the tube body 1, in order to increase a capillary transmission area. As shown in FIG. 5, instead of forming the round air flow holes 220, there are a plurality of cut-outs 220′ formed on each capillary transmission surface 211.

As shown in FIG. 6 and FIG. 7, there are a plurality of grooves 101 that are radially threaded, in right helical direction, left helical direction, or both, or even irregularly, on the inner wall of the tube body 1. A depth of the groove 101 is less than 0.03 mm, and is usually less than 30% of a thickness of the tube body 1 as well, as shown in FIG. 7. As it can be seen, since the grooves 101 are formed on the inner surface of the tube body 1, the structure of the grooves 101 will not interfere the formation of the vapor channel 100. Meanwhile, the grooves 101 are radially threaded to surrounding on the inner wall of the tube body 1, the liquid working fluid can flow back to the capillary structure 2; on the other hand, the liquid working fluid flowing back axially (along the longitudinal direction) is through the capillary structure 2 as well. Therefore, the grooves 101 can provide auxiliary help to the capillary structure 2 to form a capillary transmission net that totally covers totally the inner wall of the tube body 1.

Accordingly, by means of above described structure, a heat pipe with an ultra-thin capillary structure is achieved.

Although the invention has been disclosed and illustrated with reference to particular embodiments, the principles involved are susceptible for use in numerous other embodiments that will be apparent to persons skilled in the art. This invention is, therefore, to be limited only as indicated by the scope of the appended claims. 

What is claimed is:
 1. A heat pipe with an ultra-thin capillary structure, comprising: a tube body (1), being hollow and flat; and a capillary structure (2), being in the tube body (1) and shaped as a thin plate, having an adhering surface (20) attached on a partial portion of an inner wall of the tube body (1), and a forming surface (21) corresponding to the adhering surface (20), a vapor channel (100) being formed between the forming surface (21) and the inner wall of the tube body (1); wherein the forming surface (21) further comprises an abutting surface (210) elongated along a longitudinal direction of the vapor channel (100), and at least one capillary transmission surface (211) extending from a side of the abutting surface (210) to connect to the adhering surface (20), the capillary transmission surface (211) being gradually inclined between the adhering surface (20) and the abutting surface (210).
 2. The heat pipe with an ultra-thin capillary structure according to claim 1, wherein a thickness of the flat tube body (1) is under 0.5 mm.
 3. The heat pipe with an ultra-thin capillary structure according to claim 1, wherein the capillary structure (2) is made by selecting from a group consisting of knit, fiber and sintered metal powders and their combination.
 4. The heat pipe with an ultra-thin capillary structure according to claim 1, wherein a porosity of the forming surface (21) is gradually reduced as the forming surface (21) is extended toward the adhering surface (20).
 5. The heat pipe with an ultra-thin capillary structure according to claim 1, wherein two sides of the abutting surface (210) have two capillary transmission surfaces (211), respectively.
 6. The heat pipe with an ultra-thin capillary structure according to claim 5, wherein the two capillary transmission surfaces (211) are symmetrical to each other.
 7. The heat pipe with an ultra-thin capillary structure according to claim 1, wherein a bare area (22) is formed at a portion of the capillary structure (2) by removing corresponding capillary transmission surface.
 8. The heat pipe with an ultra-thin capillary structure according to claim 1, wherein the capillary transmission surface (211) has a plurality of air flow holes (220) exposing the inner wall of the tube body (1).
 9. The heat pipe with an ultra-thin capillary structure according to claim 1, wherein the capillary transmission surface (211) has a plurality of cut-outs (220′) exposing the inner wall of the tube body (1).
 10. The heat pipe with an ultra-thin capillary structure according to claim 1, wherein the capillary structure (2) has a plurality of grooves (101) that are radially threaded on the inner wall of the tube body (1), a depth of the groove (101) being less than 30% of a thickness of the tube body (1).
 11. The heat pipe with an ultra-thin capillary structure according to claim 10, wherein the depth of the thread (101) is less than 0.03 mm. 